css实现垂直居中 - 4种常见方法

flex

html:

<div class="container">
    <div class="box"></div>
</div>

css:

.container{
    width: 100%;
    height: 500px;
    display: flex;  //默认row方向
    justify-content: center;  //平行row方向居中对齐
    align-items: center;  //垂直row方向居中对齐
    background-color: antiquewhite;
}
.box{
    width: 50px;
    height: 50px;
    background-color: red;
}

绝对定位

html:

<div class="container">
    <div class="box"></div>
</div>

css:

.container{
    width: 100%;
    height: 500px;
    background-color: antiquewhite;
    position: relative;
}
.box{
    width: 50px;
    height: 50px;
    background-color: red;
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    bottom: 0;
    margin: auto;
}

absolute + transform

html:

<div class="container">
    <div class="box"></div>
</div>

css:

.container{
    width: 100%;
    height: 500px;
    background-color: antiquewhite;
    position: relative;
}
.box{
    width: 50px;
    height: 50px;
    background-color: red;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

absolute + calc

html；

<div class="container">
    <div class="box"></div>
</div>

css:

.container{
    width: 100%;
    height: 500px;
    background-color: antiquewhite;
    position: relative;
}
.box{
    width: 50px;
    height: 50px;
    background-color: red;
    position: absolute;
    top: calc(50% - 25px);
    left: calc(50% - 25px);
}